The present invention relates to composite extrusions for use on automotive vehicles. More particularly, the present invention is directed toward a composite extrusion comprising a rigid core embedded within a thermoplastic elastomer and an outer layer comprising one or more ionomeric materials and a method for making the same.
It is known to extrude various elastomers to form moldings, such as seals, weather strips and trim strips for use on automotive vehicles. These moldings can be used in a variety of automotive applications, including glass run channels, trim strips, cutline seals, and outerbelt and inner belt seals. Depending on their design and intended use, the various extrusions can be made from a range of materials. The most popular of these materials are elastomer rubbers such as EPDM, which impart good sealing properties and improved weatherability.
Such moldings are typically black in color, due to the difficulties encountered when elastomeric materials are colored or painted. Generally, it is difficult to color or apply a gloss to many of the materials used to make vehicle seals and trim strips. Color does not hold and the resultant molding has a dull appearance.
This characteristic of most elastomeric materials can be a severe drawback, especially in modern vehicles, where there has been a great demand for various weatherseals and trim strips having show surfaces in assorted colors and glosses for aesthetic reasons. It is often required that these show surfaces be coordinated with the high gloss exterior of the vehicle in complementary colors to improve the overall appearance of the vehicle.
One approach used in the automotive industry to solve this problem is to coat an elastomer molding, often reinforced with a metal carrier, with a polyvinyl chloride (PVC), which is available in a wide range of colors, tends to be more colorfast than elastomer rubbers, and is amenable to a high gloss coating. In this method, the elastomer rubber acts as a visually hidden sealant and the PVC is applied to a visually exposed area of the molding. The PVC can be attached to the molding over the elastomer using an appropriate adhesive or a mechanical attachment.
A second approach has been to coat the metal reinforced elastomer molding with a high gloss metal foil layer. The metal foil can be coated with a clear protective polymer coating and presents an even, hard, aesthetically pleasing surface to the exterior of the vehicle.
A third approach calls for extruding the entire molding from a thermoplastic.
Although the above approaches produce acceptable results, they all suffer from various drawbacks. The production and use of a PVC as a show layer is environmentally hazardous and therefore its use requires the taking of special health and safety precautions. In addition, PVC is susceptible to scratching and offers only marginal weatherability resistance.
Likewise, the use of a metal foil show layer suffers from several drawbacks. High gloss metal is quite expensive, thus increasing the cost of the manufactured moldings. In addition, the metal may be easily dented due to its thinness. The use of a thermoplastic to manufacture the entire molding suffers from the fact that thermoplastic does not effectively seal the vehicle from weather. In addition, a thermoplastic molding is typically more expensive to manufacture than an elastomer rubber molding.
Therefore, it would be desirable to develop a molding with a show surface that is amenable to coloring or the application of a high gloss finish that is relatively inexpensive to produce and does not suffer from the above mentioned drawbacks.
In a first aspect, the invention provides a composite molding for an automotive vehicle including a core member, a main body portion comprising thermoplastic elastomer, and a show layer comprising ionomer disposed on the surface of the main body portion such that the show layer is visible from the exterior of an automotive vehicle when the molding is installed.
In a second aspect, the invention provides a molding for an automotive vehicle including a core member, a thermoplastic elastomer main body having a flange retention channel integral with an oppositely faced glass run channel, and an ionomeric show layer disposed on an outside surface of the glass run channel.
In a third aspect, the invention provides a process for forming a molding for an automotive vehicle, the process including the steps of providing a rigid core member, providing a thermoplastic elastomer, extruding the thermoplastic elastomer to form a main body member, providing an ionomer, extruding the ionomer to form a show layer on a surface of the main body member, applying a high gloss surface to the show layer, and shaping the molding to a final shape for installation in an automotive vehicle.
The invention finds particular usefulness in the manufacture of glass run channel, and outer belts or inner belts in automobiles, although other applications are also contemplated such as other vehicle trim components, weather strips, trim strips, cutline seals, greenhouse moldings, upper auxiliary and glassrun conbinations, etc.